New Trials in Prostate Cancer: Could Your Patient Benefit?

Several new clinical trials in prostate cancer have opened in recent months. Maybe one of your patients is eligible to participate?

Prostate cancer at high risk for biochemical recurrence following radical prostatectomy and/or radiation therapy. Adult patients with this diagnosis can join a randomized, double-blind, placebo-controlled phase 3 study evaluating darolutamide (Nubeqa) plus androgen deprivation therapy (ADT) against ADT alone. For up to 2 years, one group of participants will take twice-daily tablets of darolutamide, a nonsteroidal antiandrogen approved in 2019, in combination with ADT. A second group will take placebo plus ADT. Sites in California, Colorado, and worldwide started recruiting for 750 participants in April 2023; study centers across 19 other states in the US are gearing up. The primary outcome measure is radiological progression-free survival (PFS). Overall survival and quality of life (QoL) are secondary measures. More details at clinicaltrials.gov.

Commenting on the study, Marc Garnick, MD, professor of medicine, Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, Massachusetts, said the trial “addresses an important question regarding intensification of androgen deprivation therapy with darolutamide” — specifically, whether this intensified approach is useful for a large proportion of men who experience biochemical recurrence (BCR) — rising PSA levels — after definitive localized therapy. Garnick cautioned, however, that “it will be very important for the study investigators to stratify the many characteristics of BCR — and not treat this population as a homogeneous one since initial Gleason Score, time to BCR, and PSA doubling time all may impact the outcomes.”

Metastatic castration-sensitive prostate cancer. Adults with this type of cancer can join a randomized, open-label, phase 3 trial evaluating the nonsteroidal antiandrogen apalutamide (Erleada). Apalutamide, the first treatment approved for nonmetastatic castration-resistant prostate cancer, has also been approved for patients with metastatic castration-sensitive prostate cancer. This new trial will assess an intermittent approach to providing ADT alongside apalutamide in patients with metastatic disease.

All participants will take daily apalutamide tablets plus physician’s choice of ADT for 6 months. Everyone whose PSA falls below 0.2 ng/mL will either receive apalutamide with intermittent ADT per protocol or continue to receive apalutamide plus ADT for a further 18 months or until the patient discontinues the study, whichever happens first. Recruitment of 333 participants is planned for sites in Colorado, New York, Ohio, Utah, and Germany starting in August 2023. Radiographic PFS and hot flash score are the primary endpoints. QoL and overall survival are secondary outcomes. See more details at clinicaltrials.gov.

This study “should add to our knowledge of optimal treatment” for metastatic castrate-sensitive prostate cancer,” Garnick said. However, “this is a very heterogenous population of patients and how they get to the [diagnosis] of metastatic castrate-sensitive prostate cancer is important,” Garnick noted. “The sample size and stratifications need to be well studied for this study to provide any meaningful data.”

Localized intermediate- or high-risk prostate cancer. People with one of these clinical scenarios who have not yet had stereotactic body radiation therapy (SBRT) or a prostatectomy are eligible for a randomized, open-label, phase 2 study. This National Cancer Institute (NCI) trial is looking at whether the experimental immunocytokine M9241 can enhance the effectiveness of SBRT. M9241 is designed to assist the immune system to fight cancer by boosting the activity of T cells at necrotic sites in the tumor.

All participants will receive standard-of-care ADT. One group of people will also receive three subcutaneous injections of M9241 at 4-weekly intervals in deescalating doses, then 10 days of standard SBRT, followed by another three injections of M9241 at the highest tolerable dose. A second group will only undergo SBRT. The National Institutes of Health Clinical Center in Bethesda, Maryland, started recruiting the trial’s 65 participants in June 2023. The primary endpoints are the doses of M9241 in combination with ADT that are safe and tolerable, and T-cell clonality (a measure of immunologic activity). Overall survival and QoL will not be tracked. More details are available at clinicaltrials.gov.

“The M9241 study is very important,” said Garnick, explaining that he hopes the trial will add to the growing knowledge about the interactions of radiation and its effects on the immune system.

Confirmed prostate cancer. People with prostate cancer eligible for triplet or doublet ADT combination therapy can join a randomized, single-masked, phase 2 NCI investigation of bright white light therapy for ADT-associated fatigue and depression. All participants will receive standard-of-care ADT combination therapy for up to a year. One group of participants will use AYOpro glasses, a commercial bright white light therapy, daily as ADT starts (“immediate” therapy). A second set of people will start using the glasses after 6 months of ADT therapy (“delayed” therapy). The City of Hope Medical Center in Duarte, California, planned to start welcoming the trial’s 210 participants in August 2023. Fatigue is the primary endpoint, QoL is a secondary endpoint, and overall survival will not be recorded. More details are available at clinicaltrials.gov.

“Fatigue is an important feature of cancer therapies in general and any approach to lessen the impact of fatigue should be welcome,” Garnick said. However, “it would have been helpful” if the official description of the trial had provided more information on the rationale for testing bright white light therapy in prostate cancer.

Metastatic castration-resistant prostate cancer. Adults with this diagnosis who have been treated with one prior androgen receptor axis-targeted therapy (ARAT) can enter a randomized, open-label, phase 2 trial to determine the best dose of the antibody-drug conjugate vobramitamab duocarmazine (MacroGenics). This experimental drug is designed to deliver an alkylating agent that promotes cell death in solid tumors expressing B7-H3. The B7-H3 protein rarely appears in normal tissues but is expressed at high frequency in 60% of cancers.

For approximately 2 years, participants will receive one of two doses of intravenous vobramitamab duocarmazine every 4 weeks. The trial opened in June 2023, looking to recruit 100 participants across nine states in the US and eight other countries. The primary outcome measure is radiographic PFS. Overall survival and QoL will not be assessed. More details at clinicaltrials.gov.

Localized or biochemically recurrent prostate cancer. Adults in this position who have not received prior GnRH agonist or antagonist therapy are being recruited for a randomized, single-masked, phase 2 study comparing QoL among patients taking ADTs relugolix (Orgovyx, Relumina) and leuprolide acetate for depot suspension (Lupron Depot). For up to 1 year, people in the trial will either take daily tablets of relugolix or receive injections of leuprolide every 3 months. Three study sites in Massachusetts are due to open their doors in August 2023, seeking 110 participants. The study will assess various measures of QoL. Overall survival will not be measured. More details at clinicaltrials.gov.

This study is “sort of plain vanilla,” Garnick said. Although “the objectives of the study are important,” he noted, “the study number is small and unlikely to show any meaningful differences,” even if differences do exist.

All trial information is from the National Institutes of Health US National Library of Medicine (online at clinicaltrials.gov). Garnick reports no relevant financial relationships. He is editor-in-chief of the Harvard Medical School Annual Report on Prostate Diseases, for which he receives an honorarium. 

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